The present invention relates to a method of manufacturing ceramic electronic components such as multi-layered ceramic capacitors and the like.
A multi-layered ceramic capacitor, which one of a line among the ceramic electronic components, is shown in a partially cut-away perspective view in FIG. 8. The multi-layered ceramic capacitor comprises a plurality of dielectric layers 1, a plurality of conductive layers 2 and at least two external electrodes 3. Each of the conductive layers 2 is connected alternately to respective electrode among the two external electrodes 3.
A conventional method of manufacturing multilayered ceramic capacitors is described below.
Metallic paste, which later becomes the conductive layer 2, is printed through a printing process in a certain specific pattern on a ceramic sheet, or the dielectric layer 1. A plurality of the ceramic sheets having the metallic paste printed thereon are stacked together so that the conductive layers 2 face to each other with a ceramic sheet interposing in between, for forming a multi-layered body.
Then the multilayered body is sintered, and then the external electrode 3 is provided at both ends of the sintered body covering the exposed conductive layers 2.
Recently, thickness of the dielectric layer is becoming thinner in order to increase the capacitance of a multi-layered ceramic capacitor. An example of the thinner dielectric layer is disclosed in the Japanese Patent Laid-open Publication No. H5-190043, which discloses a ceramic sheet formed of polyethylene and ceramic component.
The ceramic sheet, however, has a significantly high porosity as compared with generally used ceramic sheets manufactured with ceramic component and vehicle (organic components such as resin, plasticizer and organic solvent). As a result, if the sheets are used in a conventional manufacturing procedure for multi-layered ceramic capacitors, the sheet allows the metal component printed thereon to permeate into the ceramic sheet.
A problem with the conventional manufacturing method is short-circuiting between the conductive layers 2 caused by the metallic component permeated inside the ceramic sheet.
The problem is not specific to the multi-layered ceramic capacitors, but it has been shared also by other kinds of multi-layered ceramic components. The present invention addresses the above problem, and aims to provide a method of manufacturing ceramic electronic components that eliminates defects due to the short-circuiting.
A method of the present invention for manufacturing ceramic electronic components comprises the following processing steps;
a first process for providing a ceramic sheet containing at least ceramic component and polyethylene and providing a conductive layer containing metal component and vehicle therefor and is formed on a base film;
a second process for stacking said conductive layer formed on said base film on said ceramic sheet so that the conductive layer makes contact with the ceramic sheet and pressing them from above the base film, and then peeling the base film off;
a third process of disposing said ceramic sheet on the conductive layer;
a fourth process for stacking said conductive layer formed on said base film on the ceramic sheet and pressing them from above the base film, and then peeling the base film off;
a fifth process for forming a laminated body by repeating said third process and said fourth process; and
a sixth process of sintering the laminated body.
Since the metallic paste is not printed directly on a ceramic sheet, but it is first printed on a base film to form a conductive layer and then the conductive layer is transferred on a ceramic sheet, the metallic paste is prevented from permeating into the ceramic sheet during printing. Namely, intrusion of conductive layer into ceramic sheet is suppressed.
With the manufacturing method of present invention, the defects due to short-circuit between the electrode layers can be avoided among the multi-layered ceramic electronic components. Production yield may be increased. The method of manufacturing of the present invention is significantly effective with production of multi-layered chip capacitors, where thickness of ceramic sheet is very thin and the number of stacked layer is large.